An IC chip is electrically connected to a printed circuit board by a mounting method such as a wire bonding method, a TAB method or a flip-chip method.
In the wire bonding method, an IC chip is die-bonded to a printed circuit board by adhesive or the like, the pads of the printed circuit board are connected to the pads of the IC chip by wires such as metallic wires and then a sealing resin such as a thermosetting resin or a thermoplastic resin is applied to protect the IC chip and the wire.
In the TAB method, wires referred to as leads are connected in the block by a solder or the like and then the bumps of an IC chip and the pads of a printed circuit board are sealed by a resin.
In the flip-chip method, the pads of an IC chip are connected to the pads of a printed circuit board by through bumps and the gaps between the bumps and the respective pads are filled with a resin.
In each of these mounting methods, however, the IC chip and the printed circuit board are electrically connected to each other through lead members (wires, leads or bumps) for connection therebetween. These lead members tend to be cut off and eroded, making the connection of the printed circuit board to the IC chip cut off or causing malfunctions.
In addition, in each of these mounting methods, a sealing thermoplastic resin such as an epoxy resin is employed to protect the IC chip. However, if bubbles are contained at the time of filling the resin, then the lead members are broken, the IC pads are eroded and reliability of the IC chip is deteriorated due to the bubbles. To seal the IC chip or the like by a thermoplastic resin, it is required to create resin filling plungers and metallic molds in accordance with the respective components of the printed circuit board. Further, in case of employing a thermosetting resin, it is necessary to select a thermosetting resin in view of the materials of the lead members, a solder resist and the like, thereby disadvantageously causing cost increase.